Stator and torque converter

ABSTRACT

It is an object of the present invention to inhibit generation of a vortex in the position where operating oil separates from a stator and to increase a capacity coefficient by allowing the operating oil to efficiently flow from a turbine to an impeller. A torque converter stator of the present invention is configured to regulate the flow of operating oil returning from a turbine to an impeller within a torque converter. The torque converter stator includes an annular stator shell, a plurality of stator blades and an annular stator core. The stator blades are radially extended from the stator shell. The stator blades respectively include a corrugated operating-oil outlet-side edge. The stator core is disposed on the outer peripheries of the stator blades.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This U.S. National stage application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2009-033618 filed in Japan on Feb. 17, 2009. The entire disclosure of Japanese Patent Application No. 2009-033618 is hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a stator, particularly to a stator for regulating flow of operating oil returning from a turbine to an impeller within a torque converter. Further, the present invention relates to a torque convertor, particularly to a torque convertor for transmitting torque from an engine to a transmission via fluid.

BACKGROUND ART

The torque convertors generally include a front cover, an impeller, a turbine, and a stator. Torque is transmitted from the engine to the front cover. The torque transmitted to the front cover is subsequently transmitted to the impeller. When power is transmitted to the impeller, the impeller is rotated and operating oil is moved to the turbine. The turbine is rotated by the operating oil moved thereto. Torque is herein transmitted from the turbine to a transmission-side shaft and the transmission-side shaft is accordingly rotated. The operating oil residing in the turbine is then returned to the impeller through the stator.

The stator is herein a mechanism configured to regulate flow of the operating oil returning to the impeller from the turbine. The stator is disposed between the inner radial part of the impeller and that of the turbine. The stator mainly includes an annular stator shell, a plurality of stator blades disposed on the outer peripheral surface of the stator shell, and an annular stator core fixed to the tips of the plural stator blades. The stator shell is supported by a stationary shaft through a one-way clutch (Patent Literature 1).

Japan Laid-open Patent Application Publication No. JP-A-2001-355701 (Patent Literature 1) is an example of the related art.

SUMMARY Technical Problems

Here, focusing on the fluid flow in the vicinity of the stator within the well-known torque converters as described in Patent Literature 1, the operating oil separates from the blades of the stator at the fluid outlet of the blades and its periphery. A vortex is herein generated in the downstream (i.e., the impeller side) of the blades. When the vortex is thus generated, the transmission loss is increased in the torque transmission capacity by the operating oil. The capacity coefficient of the torque converter is thereby reduced, and the torque transmission efficiency is deteriorated.

It is an object of the present invention to inhibit generation of a vortex in the position where the operating oil separates from the stator and to increase the capacity coefficient by allowing the operating oil to efficiently flow from the turbine to the impeller.

Solution to Problems

A torque converter stator according to a first aspect of the present invention is configured to regulate the flow of an operating oil returning from a turbine to an impeller within a torque converter. The torque converter stator includes an annular shell, a plurality of blades, and an annular core. The blades radially extend from the annular shell. Each of the blades includes a corrugated operating-oil outlet-side edge. The core is disposed on the outer peripheries of the blades.

According to the torque converter stator of the first aspect of the present invention, the outlet-side edge of each blade has a corrugated shape. Therefore, the flow rate of the operating oil will be irregular on the outlet-side of each blade. Therefore, not a large vortex but a number of relatively small vortices are herein generated unlike the well-known stator. In addition, the plural vortices act to cancel out each other. Therefore, it is possible to inhibit efficiency reduction due to generation of vortices.

A torque converter stator according to a second aspect of the present invention relates to the torque converter stator according to the first aspect of the present invention. In the torque converter stator, each of the blades includes a plurality of concaves on the operating-oil outlet-side edge. Each of the concaves is recessed in a blade transverse direction with respect to an imaginary straight line connecting a shell-side end and a core-side end in the respective blades. According to the torque converter stator of the second aspect of the present invention, it is possible to achieve the same advantageous effect as that achieved by the torque converter stator of the first aspect of the present invention.

A torque converter stator according to a third aspect of the present invention relates to the torque converter stator according to the first aspect of the present invention. In the torque converter stator, each of the blades includes a plurality of convexes on the operating-oil outlet-side edge. The convexes protrudes in a blade transverse direction with respect to an imaginary straight line connecting a shell-side end and a core-side end in the respective blades. According to the torque converter stator of the third aspect of the present invention, it is possible to achieve the same advantageous effect as that achieved by the torque converter stator of the first aspect of the present invention.

A torque converter stator according to a fourth aspect of the present invention relates to the torque converter stator according to one of the first to third aspects of the present invention. In the torque converter stator, the corrugated shape of the respective blades is formed by setting a ratio of an entire concave/convex height h with respect to an entire radial width H to be in a range of 3 to 20%.

A torque converter according to a fifth aspect of the present invention is configured to transmit torque from an engine to a transmission via a fluid. The torque converter includes an impeller, a turbine, and a stator. The impeller is configured to receive the torque inputted from the engine. The turbine is opposite to the impeller while being allowed to output torque to the transmission. The stator is related to the stator according to one of the first to fourth aspects of the present invention. The stator is disposed between an inner radial part of the impeller and an inner radial part of the turbine.

Advantageous Effects of the Invention

According to the aforementioned present invention, generation of an enormous vortex can be inhibited in the position where the operating oil separates from the stator, and the capacity coefficient can be thereby increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic vertical cross-sectional view of a torque converter as an exemplary embodiment of the present invention.

FIG. 2 is a partial front view of a stator.

FIG. 3 is a partial external perspective view of the stator.

FIG. 4 is a chart showing a characteristic comparison between a torque converter using stator blades of the exemplary embodiment of the present invention and a well-known torque converter.

FIG. 5 is a diagram illustrating a stator blade of another exemplary embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

[Basic Structure of Torque Converter]

FIG. 1 is a schematic vertical cross-sectional view of a torque converter 1 adopting an exemplary embodiment of the present invention. The torque converter 1 is a device configured to transmit torque from a crankshaft (not illustrated in the figure) of an engine to an input shaft (not illustrated in the figure) of a transmission. The engine (not illustrated in the figure) is disposed on the left side in FIG. 1 whereas the transmission (not illustrated in the figure) is disposed on the right side of FIG. 1. A line O-O depicted in FIG. 1 is the rotation axis of the torque converter 1.

The torque converter 1 includes a torus 5 formed by three types of blade wheels (i.e., an impeller 2, a turbine 3, and a stator 4), and a lock-up device 6.

A front cover 10 is a disc member disposed closer to the tip of the engine crankshaft. A center boss 11 is welded to the inner radial part of the front cover 10. A plurality of nuts 12 is fixed to the outer radial part of the engine-side surface of the front cover 10, while being circumferentially disposed at equal intervals.

The front cover 10 includes an outer peripheral tubular portion 13 on the outer periphery thereof. The outer peripheral tubular portion 13 axially extends towards the transmission. The outer peripheral edge of an impeller shell 15 of the impeller 2 is welded to the tip of the outer peripheral tubular portion 13. Consequently, the front cover 10 and the impeller 2 form a fluid chamber that operating oil (fluid) is filled in the interior thereof.

The impeller 2 mainly includes the impeller shell 15, a plurality of impeller blades 16, and an impeller hub 17. The impeller blades 16 are fixed to the inside of the impeller shell 15. The impeller hub 17 is fixed to the inner radial part of the impeller shell 15. An annular impeller core 18 is fixed to the inner edges of the plural impeller blades 16. Each impeller blade 16, which is formed in a circular-sector shape, has a crescent-shaped center part. Therefore, the cross-sectional shape of the impeller core 18 is matched with the shape of the center part of each impeller blade 16.

The turbine 3 is axially opposite to the impeller 2 within the fluid chamber. The turbine 3 includes a turbine shell 20, a plurality of turbine blades 21, a turbine core 22, and a turbine hub 23. The turbine shell 20 is an annular member that the inner radial part thereof is welded to turbine hub 23. The turbine blades 21 are fixed to the inside of the turbine shell 21. The plural turbine blades 21 are circumferentially aligned. The turbine core 22 is disposed on the tips (inner edges) of the turbine blades 21. The turbine hub 23 is attached onto a transmission-side shaft while being prevented from rotating relative to the transmission-side shaft. The turbine hub 23 includes a tubular portion 23 a, and a disc flange 23 b. The tubular portion 23 a is disposed on the outer peripheral side of the transmission-side shaft. The flange 23 b radially protrudes outwards from a substantially axial center part of the tubular portion 23 a.

The stator 4 is a mechanism configured to regulate flow of the operating oil returning from the turbine 3 to the impeller 2. The stator 4 is a member integrally formed by casting of resin, aluminum alloy or the like. The stator 4 is disposed between the inner radial part of the impeller 2 and that of the turbine 3. The stator 4 mainly includes an annular stator shell 25, a plurality of stator blades 26 and an annular stator core 27. The plural stator blades 26 are disposed on the outer peripheral surface of the stator shell 25. The stator core 27 is fixed to the tips of the plural stator blades 26. The stator shell 25 is supported by a stationary shaft (not illustrated in the figure) through a one-way clutch 30. Further, a retainer 31 is disposed on the axial engine side of the one-way clutch 30. The retainer 31 holds the one-way clutch 30 while being disposed between the one-way clutch 30 and the flange 23 b of the turbine hub 23. Further, the retainer 31 includes a plurality of radially extended grooves on a surface thereof that makes contact with the flange 23 b. The operating oil is thereby allowed to flow from the inner peripheral side to the outer peripheral side.

A thrust bearing 32 is disposed between the impeller hub 17 and the stator shell 25. Further, a sealing member 33 is disposed between the inner race of the one-way clutch 30 and the outer periphery of the tubular portion 23 a of the turbine hub 23.

[Stator Blades]

Next, the stator blades 26 will be explained in detail with reference to FIGS. 2 to 4. As illustrated in a partial enlarged view of FIG. 2, each stator blade 26 is a plate member with a predetermined width connecting the stator shell 25 and the stator core 27. Each stator blade 26 includes an inlet-side edge and an outlet-side edge. The inlet-side edge is formed for linearly connecting a shell-side end S1 and a core-side end C1. On the other hand, the outlet-side edge is not formed for connecting a shell-side end S2 and a core-side end C2 by an imaginary straight line M. The outlet-side edge includes three concaves 26 a recessed transversely inwards (towards the inlet) with respect to the imaginary straight line M. Each concave 26 a is recessed in a circular-arc shape. In other words, each stator blade 26 includes two convexes 26 b on the outlet-side edge. Each convex 26 b is tapered along the flow direction of the operating oil. Thus, the outlet-side edge includes concaves/convexes in the blade transverse direction and is thereby formed in a corrugated shape.

The concaves 26 a and the convexes 26 b are not herein formed due to manufacturing errors but formed purposefully. In FIG. 2, the length h of each concave 26 a (i.e., the height of each convex 26 b) is herein preferably set to be in a range of 3 to 20% of the length H of an imaginary straight line connecting the shell-side end S2 and the core-side end C2 (i.e., the entire radial width).

[Lock-up Device]

Next, the lock-up device 6 will be explained. The lock-up device 6 mainly includes a piston 40 and a damper mechanism 41.

The piston 40 is a disc member disposed between the front cover 10 and the turbine 3. An inner peripheral tubular portion 42 is formed in the inner periphery of the piston 40 while being axially extending towards the transmission. The inner peripheral tubular portion 42 is supported on the outer peripheral surface of the turbine hub 23 while being rotatable relative to the turbine hub 23 and axially movable. It should be noted that the axial transmission-side end of the inner peripheral tubular portion 42 is abutted to the flange 23 b of the turbine hub 23 and the inner peripheral tubular portion 42 is restricted from axially moving towards the transmission up to a predetermined position. A sealing ring 43 is disposed on the outer peripheral surface of the turbine hub 23. The sealing ring 43 seals axial adjacent spaces in the inner periphery of the piston 40.

The outer radial part of the piston 40 functions as a clutch coupling portion. In other words, an annular friction facing 45 is fixed to the engine-side surface of the outer radial part of the piston 40. The friction facing 45 is opposite to an annular flat friction surface formed on the inner surface of the outer radial part of the front cover 10.

The damper mechanism 41 includes a retaining plate 46, a driven plate 47, and a plurality of torsion springs 48. The retaining plate 46 is fixed to the turbine 3 side surface of the outer radial part of the piston 40 by a plurality of rivets 49. The retaining plate 46 includes cut-and-bent portions for accommodating and supporting the torsion springs 48. The plural torsion springs 48 are circumferentially extended coil springs. The torsion springs 48 are accommodated in the retaining plate 46 while the both circumferential ends thereof are supported. The driven plate 47 is an annular plate fixed to the outer radial part of the turbine shell 20 of the turbine 3. The driven plate 47 extends towards the front cover 10. The driven plate 47 includes protruded claws 47 a to be engaged with the both circumferential ends of the respective torsion springs 48.

[Actions]

Torque is transmitted from the crankshaft of the engine (not illustrated in the figures) to the front cover 10 and the impeller 2. The operating oil is driven by the impeller blades 16 of the impeller 2 and thereby rotates the turbine 3. Rotation of the turbine 3 is outputted to the input shaft of the transmission (not illustrated in the figures) through the turbine hub 23. In flowing from the turbine 3 to the impeller 2, the operating oil flows to the impeller 2 through a path defined by the stator shell 25 and the stator core 27 of the stator 4.

When the operating oil passes through the stator 4, the stator blades 26 restrict the flow of the operating oil. The operating oil separates from the stator blades 26 at the outlet-side edges of the stator blades 26. The outlet-side edge of each stator blade 26 herein includes a plurality of concaves/convexes, and is thereby formed in a corrugated shape. Accordingly, the flow rate of the operating oil is irregular in a flow direction from the outlet-side edge to the impeller 2. In other words, the flow rate of the operating oil varies in accordance with the concaves/convexes forming the corrugated shape. Therefore, relatively small vortices are irregularly generated while a large vortex, which is generated in the well-known stator blades, is not easily generated. As a result, thus generated vortices cancel out each other.

With the corrugated outlet-side edges of the stator blades 26, it is thus possible to inhibit generation of a vortex and inhibit reduction in a capacity coefficient. FIG. 4 shows a characteristic comparison between the torque converter using the well-known stator blades and the torque converter using the stator blades 26 of the present exemplary embodiment. In FIG. 4, characteristics of the present exemplary embodiment are depicted with a solid line, whereas characteristics of the well-known torque converter are depicted with a broken line. More specifically, the following characteristics are set for the present exemplary embodiment and the well-known torque converter. As to the present exemplary embodiment, a capacity coefficient is set as a characteristic Cc1; a torque ratio is set as a characteristic T1; and a torque transmission efficiency is set as a characteristic η1. As to the well-known torque converter, a capacity coefficient is set as a characteristic Cc2; a torque ratio is set as a characteristic T2; and a torque transmission coefficient is set as a characteristic η2.

As is obvious from FIG. 4, the torque converter using the stator blades 26 of the present exemplary embodiment can increase the capacity coefficient while keeping the efficiency roughly at the same level as that of the well-known torque converter.

When the operating oil residing in the space between the front cover 10 and the piston 40 is herein drained from the inner peripheral side, the piston 40 is moved towards the front cover 10 by a hydraulic difference and the friction facing 45 is pressed onto the friction surface of the front cover 10. Consequently, torque is directly transmitted from the front cover 10 to the turbine hub 23 through the lock-up device 6.

Other Exemplary Embodiments

The present invention is not limited to the aforementioned exemplary embodiment. A variety of changes or modifications can be herein made without departing from the scope of the present invention.

FIG. 5 illustrates one of stator blades of another exemplary embodiment. Each stator blade 26′ herein includes a plurality of convexes 26 b′ on the outlet-side edge thereof. Each convex 26 b′ protrudes transversely outwards with respect to an imaginary line M connecting a shell-side end S2 and a core-side end C2 in each stator blade 26′. Each convex 26 b′ is tapered along the flow direction of the operating oil. Further, concaves 26 a′ are formed for alternately aligning with the convexes 26 b′. Accordingly, the outlet-side edge of each stator blade 26′ has an entirely corrugated shape.

INDUSTRIAL APPLICABILITY

According to the aforementioned present invention, generation of an enormous vortex can be inhibited in the position where the operating oil separates from the stator, and a capacity coefficient can be thereby increased.

General Interpretation of Terms

In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 

1. A torque converter stator configured to regulate flow of an operating oil returning from a turbine to an impeller within a torque converter, the torque converter stator comprising: an annular shell; first and second blades configured around the annular shell and radially extending from the annular shell, the first blade extending in a first direction, the first blade including a first operating-oil outlet-side edge, the second blade including a second operating-oil outlet-side edge, the first and second blades being corrugated; and a first annular core disposed on an outer periphery of the first blade and an outer periphery of the second blade.
 2. The torque converter stator recited in claim 1, wherein the first blade including a first concave being recessed in a second direction which is perpendicular to the first direction.
 3. The torque converter stator recited in claim 1, wherein the first blade including a first convex bulging in a third direction opposite to the second direction.
 4. The torque converter stator recited in claim 1, wherein a ratio of a height h to a width H is in a range of 3 to 20%, where the height h is between a tip of the first convex and a bottom of the first concave, and the width H is a length in a longitudinal direction of the first blade.
 5. A torque converter configured to transmit torque from an engine to a transmission via a fluid, the torque converter comprising: an impeller configured to receive the torque inputted from the engine; a turbine configured opposite to the impeller, the turbine configured to output the torque to the transmission; and a stator disposed between an inner radial part of the impeller and an inner radial part of the turbine, the stator including: an annular shell, first and second blades radially configured around the annular shell and extending from the annular shell, the first blade extending in a first direction, the first blade including a first operating-oil outlet-side edge, the second blade including a second operating-oil outlet-side edge, the first and second blades being corrugated, and a first annular core disposed on an outer periphery of the first blade and an outer periphery of the second blade.
 6. The torque converter recited in claim 5, wherein the first blade includes a first concave being recessed in a second direction which is perpendicular to the first direction.
 7. The torque converter recited in claim 5, wherein the first blade including a first convex bulging in a third direction opposite to the second direction.
 8. The torque converter recited in claim 5, wherein a ratio of height h and a width H is in a range of 3 to 20%, where the height h is between a tip of the first convex and a bottom of the first concave, and the width H is a length in a longitudinal direction of the first blade. 